Iphone 5S does not associate with 5 Ghz frequency

has anyone met issues when using Iphone 5S with Ruckus 7363 access point, when broadcasting the 2.4GHz frequency and the 5 GHz frequency? (firmware version 9.7.1.0.17) The issue : when the Iphone tries to associate with the access point, it keeps failing, and thus does not even try to associate using the 2.4 GHz frequency.

The SSID is open. However we did not test with PSK (technically they do want an open SSID).The last test I did was to disable for a few minute the broadcast of the SSID over the 5Ghz frequency, and the iphone connected right after that (using 2.4 ghz)

By TAC case, do you mean a specific ticket that I should open ?I made the suggestion to the customer to perform the upgrade and let us know if any other issue happen(as he said he had a pending upgrade on his device)